Gaseous discharge tubes such as fluorescent lamps or neon tubes have generally been driven by alternating currents. In the case of neon tubes the voltage applied to the neon tubes is generally supplied at a high level in the vicinity of 5,000 to 15,000 volts.
Various attempts have heretofore been made to drive said gaseous discharge tubes by a direct current.
For example U.S. Pat. No. 4,400,184 relates to apparatus for operating gaseous discharge tubes such as fluorescent lamps on a direct current from a source of alternating current.
Moreover, U.S. Pat. No. 4,745,342 teaches a signal transformer which has a pair of secondary windings which are used to drive a pair of tandem connected FET switches which, in turn, are connected across a second direct current supply which has a high direct current voltage derived from the input alternating current voltage.
Furthermore, U.S. Pat. No. 3,753,040 teaches a strobing circuit for a fluorescent lamp where a triac connects the lamp to a ballast winding, the triac being controlled by a two transistor multi-vibrator supplied with direct current voltage through a diode connected to a tap of the ballast winding. The resistor is connected in parallel with the triac to conduct a small amount of current when the triac is non-conductive and to keep the lamp ionized.
Yet another apparatus is disclosed by U.S. Pat. No. 3,120,347 which relates to apparatus and systems for dimming and operating gaseous discharge lamps such as fluorescent lamps.
Finally, U.S. Pat. No. 4,748,381 teaches a circuit arrangement for alternating current operation of gas discharge lamps.
These and other prior art devices present relatively complicated structures which are generally ineffective to produce an efficient device for energizing neon tubes with a high energy direct current generated from an alternating current source.
Furthermore, many of the prior art devices have a general limited utility as such devices operate gaseous discharge tubes within limited power capabilities and may not generally be utilized for a wide range of tube characteristics.
It is an object of this invention to produce an improved apparatus for operating gaseous discharge tubes.
It is a further object of this invention to produce a neon sign transformer for operating neon tubes at a high voltage direct current obtained by rectifying high frequency high voltage alternating current. Such neon tube transformer is capable of generating an output between 0 and 15 Kv depending on the neon tubes which are connected thereto.
The broadest aspect of this invention relates to apparatus for operating a gaseous discharge tube from an alternating current comprising: a filter for filtering electro-magnetic interference from said alternating current; a rectifier for rectifying said filtered alternating current so as to produce a low level direct current; electrical circuit driver for generating a high frequency low level drive current; an electrical power circuitry for generating a high frequency high level current for energizing said gaseous discharge tubes.
It is another aspect of this invention provides a neon sign transformer for operating a neon tube from a mains frequency alternating current comprising: a filter for filtering electromagnetic interference from said alternating current; a first rectifier for rectifying said filtered mains frequency alternating current to a low level direct current; electrical circuit driver for generating a high frequency low level alternating current including, a first transistor for generating said high frequency low level current, a drive transformer; electrical power circuitry for generating a high frequency high level alternating current for energizing said neon tube including, a second transistor for generating said high frequency power, a high voltage transformer for generating said high level voltage, and a second rectifier for generating a high frequency high voltage direct current for energizing said gaseous discharge tubes.
It is yet another aspect of this invention to provide a neon sign transformer for operating a neon tube from a 60 Hz 120 v alternating current source comprising: a filter for filtering electro-magnetic interference from said 60 Hz 120 alternating current source; an in rush current protection for protecting said transformer from said in rush current; a first rectifier for rectifying said 60 Hz 120 v alternating current to approximately 150 v direct current; electrical circuit driver powered by said 150 v direct current for generating approximately 20 KHz alternating current signal including, a first transistor for generating said 20 KHz signal, a drive transformer; and electrical power circuitry for generating approximately a 20 KHz alternating current signal and then transformed to a 0 and 15 Kv direct current in response to the characteristics of a neon tube connected thereto including, a second transistor driven by said drive transformer for generating said 20 KHz frequency, high voltage transformer for generating an output between 0 and 15 Kv, and a second rectifier for generating a direct current at a 0 to 15 Kv for energizing said neon tubes.